Abstract: In order to solve the problem of post harvest yellowing of green lemon, green lemon was treated with 1-methylcyclopropene（1-MCP） of 300 μL/L, 600 μL/L and 900 μL/L, respectively, and stored at 8 ℃. The optimal treatment concentration of 1-MCP that significantly delayed yellowing of green lemon was screened and the effects of different treatment concentration on the quality of green lemon were analyzed by electronic nose PEN3 system.The results showed that 300 μL/L 1-MCP treatment could effectively slow down the yellowing of green lemon and inhibit the decrease of soluble solids content and the increase of titratable acid content. The electronic nose analysis results showed that, the difference of volatile gas between green lemons of different storage periods could be more accurately distinguished by linear discriminant analysis（LDA）. Which suggested that 300 μL/L 1-MCP could significantly inhibit the production of volatile gas of green lemon fruit part, thus delaying the post-ripening of lemon fruit.